1. The airplane crashed when it took off.
飞机一起飞就坠毁了。
还能这样说：
The airplane fell down and broke into pieces when it took off.
The airplane crashed as soon as it took off.
应用解析：
a crash of applause 一阵掌声；
a car crash 汽车撞车的事故；
an air crash 飞机坠毁事故
2. please fasten your belt quickly.
快点系好安全带。
还能这样说：
Please fix your belt as soon as possible.
Be quick to tie your belt up.
应用解析：
pull in one's belt 俭省（束紧裤带），饿肚子
3. The plane crashed because it couldn't find the airline in the dense fog.
飞机因浓雾看不清航线而坠毁。
还能这样说：
The plane couldn't be in the right airline in the dense fog, which led to the plane crash.
The plane crashed because of the unclear airline caused by the dense fog.
应用解析：
dense东西塞得满满的，稠密的；
thick浓缩或大量东西聚集于一定空间；
close塞得毫无空隙的
4. She survived in the plane crash.
她在这次坠机事件中幸免于难。
还能这样说：
She was a survivor in the plane crash.
She was a lucky dog in the plane crash.
谚语：
All cats are grey in the dark.
黑暗之中猫都是灰色的。（人未出名时都差不多。）